A delta yoke plate is a triangular yoke fitting that distributes one insulator string's load across three attachment points. Where the crescent plate serves a two-conductor bundle on a flat curve, the delta plate's three corners form a triangular load triangle — used for V-string arrangements, three-point rigid suspensions, and assemblies where two legs converge on one string to stabilize the conductor position. The delta geometry resists the pendulum swing that plain vertical strings allow, which is why it appears on angle structures, narrow corridor lines, and substation take-off fittings where conductor position must be held tightly.
The plate works because the triangle turns suspension hardware into a braced frame. Each corner bore receives a clevis, tongue, or clamp pin; load arrives at the apex from the string and leaves through the three corners in proportions set by the geometry. For the casting, that means the apex and the corner lugs are all heavily loaded, with tension arcs running through the web. We cast the delta plate in ductile iron — chosen over gray iron for its elongation at the lugs — machine every bore, and hot-dip galvanize to ASTM A153 so the plate survives the same service life as the insulators around it.
| Item | Typical Value |
|---|---|
| Material | Ductile iron ASTM A536 (65-45-12 typical); malleable iron variant |
| Strength Rating | Ultimate tensile strength typically 25,000–50,000 lbs class at the apex assembly |
| Hole Diameter | 13/16" bores typical; 1" heavy class |
| Hole Spacing | Apex-to-corner and corner-to-corner distances per customer drawing |
| Finish | Hot-dip galvanized per ASTM A153 |
| Suitable Insulator String | Suspension strings, V-string arrangements, and polymer post assemblies |
| Weight Range | Approx. 4–9 kg per piece |
| Casting Process | Green sand casting, shot-blasted, all bores and seat faces machined |
| Standard | Manufactured to ANSI C29-series line hardware conventions |
Hang the delta plate from its apex on the string's tongue or ball fitting, then pin the corner attachments to the clamps or support fittings. Practical guidance from installation crews:
Tighten all three corner pins before tensioning the string; a loose corner lets the plate cantilever and overstress one lug.
For V-strings, verify both insulator legs land on the designed corner spacing — the delta triangle's angles set the string's stability, not field adjustment.
On angle poles, combine with yoke tension adjusting hardware to trim load sharing between corners.
Typical applications include V-string suspension on compact transmission structures, substation bus supports where the conductor must not swing, dead-end adapters converting a single string into multiple take-offs, and crossover fittings on double-circuit distribution lines. The delta's rigid triangle also suits coastal and high-wind routes, where pendulum motion accelerates insulator wear.
We produce delta yoke plates to customer drawings. Common variants include unequal leg geometries for skewed V-strings, enlarged apex lugs for twin-tongue hardware, reduced profiles for clearance-limited structures, and drilled auxiliary holes for grounding straps or arcing horns. Sample lead time is typically 3–4 weeks with first-article inspection reports for utility approval.
Each lot is inspected for: bore dimensions and triangle geometry with CMM measurement; web thickness at critical sections; hot-dip galvanizing thickness per ASTM A153; and tensile sampling to confirm the rated strength class. Large-section castings are screened for internal shrinkage before coating. Packaging uses individually wrapped plates with corner protectors, cartoned or crated per size and palletized for export.
Q: When should I choose a delta yoke plate over a crescent plate?
A: Choose delta for three-point or V-string stability requirements; choose crescent for a straightforward twin-bundle suspension where both subconductors hang level.
Q: Can the corner holes take different pin sizes?
A: Yes — corners can be machined to different bores per your drawing; 13/16" and 1" are typical.
Q: Does the delta plate work with polymer insulators?
A: Yes, via a socket y-clevis or tongue at the apex; confirm the ball/tongue class with your insulator supplier.
Send the triangle geometry and load class from your string design — our engineers will confirm the delta yoke plate casting and quote with samples.
WhatsApp: +86 185 6156 7088, or request an RFQ through the inquiry form.
Need a formal quotation? Send your Delta Yoke Plate drawing, quantity and target price through our request for quotation form — it goes straight to the foundry inbox, and we reply with a priced offer, material certificate draft and production lead time within one business day.
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Jimo District, Qingdao City, Shandong Province, China
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